Excerpt:

Last February, Astro Teller, the director of Google’s (GOOG) secretive research lab, Google X, went to seek approval from Chief Executive Officer Larry Page for an unlikely acquisition. Teller was proposing that Google buy Makani Power, a startup that develops wind turbines mounted on unmanned, fixed-wing aircraft tethered to the ground like a kite. The startup, Teller told Page, was seeing promising results, and, he added proudly, its prototypes had survived all recent tests intact.

Page approved Google X’s acquisition of Makani, which was being completed for an undisclosed amount at press time. He also had a demand. “He said we could have the budget and the people to go do this,” Teller says, “but that we had to make sure to crash at least five of the devices in the near future.”